This invention relates to method and apparatus for machining the end surface for the housing of a slant axis rotary mechanism, such as an engine, pump, compressor or the like.
Considerable difficulty is experienced in machining the end surfaces of the housings of slant axis rotary mechanisms. The degree of difficulty depends, to some extent, on whether the mechanism is a two-cycle mechanism, a four-cycle mechanism, etc.
In a four-cycle mechanism, in a developed view, the end housings will appear to be sinusoidal. Generally, they will be somewhat conical as well. Consequently, an extremely difficult task is present in machining the requisite contour.
The task is made more difficult by other practical factors concerned with operation of the mechanism. Most, if not all, such mechanisms include seals carried by a rotor, which seals traverse the end surfaces. Experience has shown that if marks remaining from machining of the surface extend generally transversely to the mean seal length, premature seal failure will occur. Conversely, when such machining marks extend generally parallel to mean seal length, the life of the seal is considerably prolonged.
In some instances, where high pressures are encountered during operation of the mechanism, particularly when used as an engine, it is desirable that the end surfaces be convex or concave to more rigidly withstand the pressures. Such rigidity minimizes deflection of the housing in response to high pressures and as a consequence, allows the use of lesser clearances between the rotor and the housing walls, thereby minimizing parasitic volume of the mechanism and increasing its efficiency. Of course, when such configurations are employed, the already difficult task of machining an undulating and conical surface as in a four-cycle slant axis rotary mechanism is considerably increased.